Sextant



Aug. 3, 1937. A. F. HEGEN-BERGER ET AL sExTA'N'r Filied July 1, 1936 2 Sheets-Sheet 1 WY. mum Ill y M M r r 4 Aug. 3, 1937. A. F. HEGENBERGER El AL 88, 97

SEXTANT Filed July 1, 1936 2 Sheets-Sheet 2 mmmimmg Patented Aug. 3, 1937 SEXTAN T Albert F. Hegenberger, Riverside, Calif., and Andrew W. Knisley, Dayton, Ohio Application July 1, 1936, Serial No. 88,412

7 Claims.

(Granted under the act of March 3, 1883, as

amended April 30,

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to instruments especially adapted for use in measuring angles and more particularly to instruments generally known as sextants or octants, depending upon the maximum angle which can'be measured.

It is a principal object of our invention to provide a simple and practical instrument of the character described whereby the angular altitude of any elevated object may be determined quickly, conveniently, and with a high degree of accuracy.

Another object of our invention is to reduce to a minimum the possibility of inadvertently observing the wrong body, through employment of both hands, for auxiliary manual adjustment of our instrument. I

Our invention also makes possible immediate or delayed reading of the angular altitude of the body referred to in the preceding paragraphs.

In our invention we have further accomplished great simplicity in the number and operation of working parts, to the end that we have produced an instrument compact in form, light in weight,

and entirely automatic in its operation.

With the foregoing and other objects in view, which will appear as the description proceeds, the invention consists of certain new and novel improvements in sextants which will be hereinafter more fully illustrated and described in the accompanying drawings and more particularly pointed out in the appended claims.

Referring to the drawings, in which numerals of like character designate similar parts throughout the several views:

We have further provided, through the use of Fig. 5 is a cross-sectional view taken on the line 5-5 of Fig. 4.

Fig. 6 is a cross-sectional view taken on the line 6-6 of Fig. 2.

Fig. '7 is a cross-sectional view taken on line 1 -1 of Fig. 1.

Fig. 8 is a wiring diagram of the electrically controlled elements of our invention.

In Figs. 1 and 2 a housing I is provided with tubular portions 2 and 3 co-axially located upon a horizontal axis .r-:c and a cover plate 4. Tubular portion 2.is provided. with aneye-piece 5 composed of lenses 6 and I mounted in a housing, 8, while the forward tubularv portion 3 is provided with a telescopic objective 9 composed of a lens I 0 mounted in a housing H. The housing I is provided with a .counting -mechanism l2, including a mask II with three equally-:spaced openings positioned parallel to axis :r- -a: (see Fig. 5). The aforesaid parts are symmetrically disposed about a vertical axis y-y, intersecting the axis :c:z: and positioned normal thereto. A plane gla'ss reflector I4 is positioned such that thepoint of intersection of the axes :r-a: and 1 y lies in the the mirrored aft surface thereof, which surface is further tilted at an angle of forty-five degrees to both of the aforesaid axes. As viewed in Fig. 2, the lower portion-of the housing I is provided PATENT OFFICE I with a single continuous opening l5, identical in- I H outer contour to the over-allconfiguration to the three openings provided in the mask and shown in Fig. 5. Six discs of the counting mechanism l2 are so disposed with reference to a hereinafter described mask placed beneath the opening l5 and with further reference to the three openings provided in the mask l3 that identical readings are recorded by the aforesaid counting mechanism [2 when viewed either through the, eye-piece 5 or through the opening l5 provided in the under portion of the housing I. Details as to disc construction and the interpretation of their reading will be dealt with below.

Referring to Figs. 3, 4, 6 and '7, a pendulum housing I6 is rotatably secured to the housing I by means of journals I1 and IS. The outer extremity of the journal I! is provided with a fixed gear l9, held in operable engagement with gears 20 and 2| rotatably secured to the cover 4 by means of flxedjournals 22 and 23. A worm segment 24 is fixed to the outer surface of the gear 2|, the assembled parts being fixed laterally with reference to the cover 4 bymeans of a c-shaped washer 25 and a pin 26 fixed to the. inner extremity of the journal 23. One half of the inner faceof the gear 2| is provided with a slot 21 within which is fixedly secured a mirror 28. It will be noted that the upper right-hand portion of the housing I6 is provided with an L-shaped lug 29 with axis of symmetry rearwardly inclined towards the eye-piece 5 of the tubular portion 2. The polished surface of the mirror 28 is similarly inclined towards the eyepiece 3 with angle of incidence to the axis :r-a: one-half magnitude of that formed between the axis of symmetry of the lug 29 and the axis :ca:. As long as a ratio of two-to-one is maintained between the gear 2| and similar gears 23 and I9, reflected prolongation of the axis of symmetry of the lug 29 in the mirror 29 will always lie parallel to the axis .1:-x.

As viewed in Fig. 7, the mid-portion of the upturned face of the lug 29 is provided with two minor spaced graduations |02a and |||2b symmetrically disposed about a central graduation 39, intersecting and lying normal to the axis of symmetry of the lug 29.

As shown in Figs. 4 and 7, the outer tip of a wire pointer 3| is so positioned with reference to the graduation 33 that the former will appear in coincidence with the latter when viewed through the eye-piece 3. The inner extremity of the wire 3| is fixed to a free pendulum 32 such that as longas the axis of symmetry of the housing I3 is maintained parallel to the vertical axis 11-11, as .viewed in Fig. 4, any deviation -of the latter axis from true vertical will cause misalignment of the outer extremity of the wire pointer 3| with the graduation 30, thus indicating that the housing is no longer being held in true horizontal". A further important fact is indicated by the aforesaid misalignment, that is, that the axis of symmetry of the aforesaid pendulum 32 has moved out of coincidence with the axis of symmetry of the housing l3, as viewed in Fig. 4. 40 Thus, regardless of the upward tilt of thehouslog during observation of celestial bodies,

through proper adjustment of the gear-chain I9,

23 and 2|, the aforesaid axes of symmetry may be readily adjusted into coincidence. Through 45 further employment of a knob 33 and suitable interconnecting gearing mechanism, it is possible to definitely record upon the counter |2 that angle of divergency of the ax|s of symmetry of the housing l6 which is required to place the axis 50 of symmetry of the pendulum in coincidence therewith and thus indicate the angle of divergency of the axis a:::: from true horizontal during observation of any predetermined celestial body or the like.

Figs. 6 and 7 show in detail the manner of mounting a pendulum 32 within the housing l3. The upper outer ends of the housing l6 are provided with knife-blocks 34-having V-shaped slots within which rest knife-blade portions 33 of the 60 pendulum 32. Referring to Figs. 6 and 7, it will be seen that an opening 36 is provided in the upper right-hand portion of the housing l6 for egress of the indicating wire 3|, the inner extremity of which is fixed to knife portion 33. Certain additional elements shown in Figs. 6 and 7 willbe referred to hereinafter.

Adjustment of gear-chain I3, 20 and 2| may be effected either manually or automatically.

Referring to Fig. 4, a small reversible motor 31 70 is secured to the upper surface of the housing by means of mounting lugs 33. An armature shaft 39 is provided at its aft extremity with a helical gear 30 and at its forward extremity with a helical gear 3|. The gear 30 is in operable 75 engagement with a helical gear 42 fixed to the inner extremity of a shaft 43. Figs. 1 and 2 show the knob 33 fixed to the outer extremity of the shaft 43. The gear ll is meshed with a helical gear 34 fixed to the inner end of a driven shaft 45. The outer extremity of the shaft 43 is provided with a helical gear 43 adapted to operatively engage a vertically disposed helical gear 41 fixed to the upper extremity of a second driven shaft 43. The lower extremity of the vertically disposed shaft 33 is provided with a helical gear 49 operatively engaging a helical gear 33 secured to the outer extremity of the counter l2, as shown in Fig. 3. I

Since the physical characteristics of the individual gears comprising the hereinabove-described gear-chain are identical, a one-to-one gear ratio obtains for secondary rotation of the counter l2 by means of primary rotation of the knob 33. The mid-portion of the vertical driven shaft 38 is provided with a helical gear 3| adapted to operatively mesh with a second gear 32 mounted on a cross-shaft 33. The pitch of the aforesaid gears has been so selected that eight rotations of the vertical driven shaft 43 are required toeifect one complete rotation of the cross-shaft 53. The rear extremity of the cross-shaft 33 is provided with a helical gear 34. A ratio of fortyfive revolutions to one revolution is maintained between the helical gear 33 and the worm segment such that three-hundred and sixty revolutions of the horizontal driven shaft 33 are required to affect one complete revolution of the gear assembly 24, 2|. Since but one revolution of gear 2| is required to effect two revolutions of the gears 23, I3 and the housing l3, it is nowevident that 180 revolutions of the knob 33 will be required to effect one complete revolution of the housing l3 about the journals l1 and I3.

During normal operation of a sextant, the alignment of its longitudinal axis varies from true horizontal to approximate vertical, 1. e., a range of zero to ninety degrees angular altitude. Therefore, each turn of the knob 33 will effect a one-half degree misalignment" correction of the axis of symmetry of the housing It with reference to true vertical of the freely hanging pendulum 32. If reference be made to the counter |2 of Figs. 2 and 5, it thus follows that the aforesaid knob adiustment will bring about six graduation changes of five minutes magnitude each, as more fully described below.

In Fig. 5, the central portion of the plane glass reflector M has been broken away sumciently to indicate that the mask 3 is provided with three equally-spaced openings 33, 33, and 51. In Figs. 5 and 9 graduation marks 33, 33, and are provided on the closed' portions of the mask l3, in plan coincident to the longitudinal axis of the counter l2, to the immediate "right" of the sextant user while looking through the eyepiece 3, as shown diagrammatically in the latter figure. The disc portion of the counter |2 lying immediately beneath the opening 31 is provided with minute graduations 3| and five minute graduations 32. It will be noted that numerals 83 (totaling twelve in number) are provided to the immediate left of each of the five-minute graduations 32 for ready identification of the latter as the same come into progressive registration with the indicator mark 33. The disc portions lying immediately beneath openings 33 and 33 are provided with ten equally spaced numerals 63 and 63, respectively. The numerals 64 characterize the first digit of a series of angular altitude readings ranging from zero to ninety degrees. The numerals 65 characterize the second digit of the aforesaid series of angular altitude readings. One complete revolution of the disc portion lying immediately beneath the 5 opening 51 will effect one-tenth revolution of the disc portion lying beneath the opening 56. In like manner, one complete revolution of the disc portion lying beneath the opening 56 will effect one-tenth revolution of the disc portion beneath the opening 55. There is thus an operative relationship between the movement of the pendulum housing I6 and the various disc elements of the counter I2, permitting exact knowledge of the angle of deviation of the axis x- -a: from true horizontal during the observation of a predetermined celestial object I03 in the manner shown in Fig. 9. If desired, hair lines I04 and I05 may be suitably inscribed upon the near surface of the plane glass reflector I4. Since all of the numerals and degree marks of Fig. 5 are viewed by inversion through the plane glass reflector I4,

it will be noted that the foregoing appear upside-down when viewed directly through the cut-away portion of the aforesaid reflector. In

Fig. 9, a mirrored reflection of the wire pointer 3|, superimposed upon central graduation the two minor spaced graduations i020. and I02b, and the top portion of the lug 29 are shown in the mirror 28, to the left of the opening 55..

30 From the reading indicated, the celestial object I03 is at zero elevation.

If Fig. 2 be viewed with the tubular portion 2 held uppermost, a direct reading duplicate of the numerals and .degree marks of Fig. 5, will be observed. The opening I5 in the housing I is sealed by a masked cover glass 66 provided with three equally-spaced openings 61, 68 and 69.

Graduation marks 10, II and 12 are provided on the non-transparent portions of the cover glass 60. Since the latter conceal the three counter discs shown in Fig. 5, each of the graduation marks 10, II and 12 appear to the left (instead of the right) of the minute graduations 6|, the five minute graduations 62 and the numerals 63, 64, and 65.

Electrical operation of .our invention may best be understood'by preliminary reference to Fig.

8. The small reversible motor 3'! is diagrammatically represented as containing a field I3 terminating in terminals 14 and 15, an armature I6, and brushes Ti and 18. It should be noted that one pole of a battery 19 and the outer extremity of the brush 'I'I have a common ground in the housing I of our invention. The outer extremity of the remaining brush l8 terminates in terminal 80, while the remaining pole of the battery I9 is connected to a two-pole, doublethrow' switch 8I.

The switch 8| forms a part of and is carried by the pendulum housing I6. In Fig. 8, contacts 82, 83, 84 and 85 are diagrammatically represented as fixed (with reference to the pendulum housing I6) and two-way contacts 86 and 81 as pivoted about a point 88. i. e., the bottoms of knife-blade portions 35 of the pendulum 32.

The two-way contacts 86 and 81 are resiliently mounted in relation to one another by means of mounting springs '89 and 90 and an insulating block 9|. Terminal 82 is connected in common to terminals 14 and 83, while terminals 84 is connected In common to terminals I5 and 85. Mounting spring 89 is connected to the ungrounded pole of the battery 19. the remaining mounting spring 90 being connected to terminal of the motor 31. From the foregoing, it is at once evident that if clockwise movement of the insulating block 9I induces current flow from the battery 19 to the terminal 15, then counterclockwise movement of the insulating block 9| will induce reversed current flow from the bat-- tery 19 to the terminal 14, thereby simultaneously reversing direction of turn of the armature I6.

Figs. 4, 6, and. '7 show actual disposition of parts diagrammatically represented in Fig. 8. 10 Referring to Fig. 4, negative terminal 93 of a jack 92 is grounded to a boss 94 of the housing I, through a toggle switch 95. The positive terminal 96 of the jack 92 is connected to the cshaped mounting spring 89, shown in Fig. 4. It 15 will be noted that the insulated block 9! supporting mounting springs 89 and is fixed to the knife blade portion 35 of the pendulum 32 by means of a vertical support 91. Each of the contacts 82, 83, 84, and 85 are backed with a 20 threaded portion 98. The threaded portions 98 are supported and adjusted by means of mounting lugs 99, insulator blocks I00 and check nuts I M. Electrical interconnection between the small reversible motor 31, the C-shaped mount- 25 ing spring 90, and the threaded portions 98 of contacts 82, 83, 84, and 85 is effected as indicated in Fig. 8.

Two methods may be used for obtaining the true elevation of a celestial or other object. The 30 sextant is hand elevated until the common axis of the tubular portions 2 and 4, thereof, is aligned with the object under observation. Assuming previous zero setting of the counter I2, an observer will thereupon visualize a duplication of Fig. 9, with the single exception that the wire pointer 3I will be superimposed upon the graduation M211, and not upon the central graduation 30, to which it must be returned if the axes of symmetry of the freely hanging pendulum 32 and 40 the pendulum housing I6 are to be brought into common coincidence with true vertical.

The first method of returning the wire pointer 3| into superimposed coincidence with the central graduation 30 consists simply in shifting the 45 handle of the toggle switch from position I06a to position I06b, as shown in Fig. 1. The electrical operation involved is fully covered, hereinabove, in connection with the description of Fi 8. 50

The second method of returning the wire pointer 3i into coincidence with the central graduation 30 consists of manually turning the knob 33in a manner fully discussed hereinabove. Each turn of the knob 33 effects a one-half de- 55 gree misalignment correction of the axis of symmetry of the housing I6 with reference to true vertical of the freely hanging pendulum 32. Thus, assuming the celestial object I03 to lie at a 15 degree elevation to true horizontal, 60'

thirty turns of the knob 33 will return the wire pointer 3| into coincidence with the central graduation and simultaneously indicate a reading of 15 degrees and no minutes upon the face of the counter I2. 65

We claim: a 1. In a sextant having a housing and a biportioned means for simultaneously producing images of an observed object and the reading of its elevation above the horizon in a common 70 focal plane, a pendulum, a supporting means for .said pendulum rotatable with respect to said housing, means associated with said pendulum and said pendulum supporting means for effecting a predetermined relation between said penclu- 75 lum and said supporting means for any angular displacement of said housing, and means associated with said pendulum supporting means for indicating the relative angular change between said pendulum supporting means and said housing. v

2. In a sextant having a housing and a bi-portioned means for simultaneously producing images of an observed object and the reading of its elevation above the horizon in a common focal plane, a pendulum, a supporting means for said pendulum rotatable with respect to said housing, electric power driven means associated with said pendulum and said pendulum supporting means for effectinga predetermined relation between said pendulum and said supporting means for any angular displacement of said housing, and means associated with said pendulum supporting means for indicating the relative angular change between said pendulum supporting means and said housing.

3. In a sextant having a housing and a biportioned means for simultaneously producing images of an observed object and the reading of its elevation above the horizon in a common focal plane, a pendulum, a housing pivotally supporting said pendulum and rotatively mounted in said first-mentioned housing, a reversible motor adapted to be electrically connected to and operated by said pendulum, said motor being responsive to relative displacements between said pendulum and said first-mentioned housing to cause equal and opposite rotation of said pendulum housing relative to said first-mentioned housing, and means associated with said pendulum housing for indicating the relative angular change between said housings.

4'. In a sextant having a housing and a biportioned means for simultaneously producing images of an observed object and the reading of its elevation above the horizon in a common focal plane, a pendulum, a housing pivotally supporting said pendulum and rotatively mounted in said first-mentioned housing, a reversing switch carried by said pendulum housing and responsive to movements of said pendulum, a reversible motor adapted to be connected to said switch such that said pendulum housing is caused to rotate in an equal and opposite direction to each relative displacement between said pendulum and said first-mentioned housing, and means associated with said pendulum housing for indicating the relative angular change between said housings.

5. In a sextant having a housing and a bi-portioned means for simultaneously producing images of an observed object and the reading of its elevation above the horizon in a common focal plane, a pendulum, a supporting means for said pendulum rotatable with respect to said housing, means to cause said pendulum supporting means to rotate in an equal and opposite direction to each relative displacement between. said pendulum and said housing,'and means associated with said pendulum supporting means for indicating the relative angular change between said pendulum supporting means and said housing.

6. In a sextant having a housing and a bi-portioned means for images of an observed object and the reading of its elevation above the horizon in a common focal plane, a pendulum, a supporting means for said pendulum rotatable with respect to said housing, means to cause said pendulum supporting means to rotate in an equal and opposite direction to each relative displacement between said pendulum and said housing, means associatedwith said pendulum and pendulum supporting means for indicating the relative angular dispositions therebetween, and means associated with said pendulum supporting means for indicating the relative angular change between said pendulum supporting means and said housing.

7. In a sextant having a housing and a bi-portioned means for simultaneously producing images of an observed object and the reading of its elevation above the horizon in a common focal plane, a pendulum, a supportingmeans for said pendulum rotatable with respect to said housing, automatic means associated with said pendulum and said pendulum supporting means for effecting a predetermined relation between said pendulum and said supporting means for any angular displacement of. said housing, and means -associated with said pendulum supporting means for indicating the relative angular change between said pendulum supporting means and said housing.

* ALBERT F. I I-llGENBER.(PIER.

ANDREW W. KNISLEY.

simultaneously producing- 

